What do we learn about Sammy in A&P?

Over the course of the story, we learn that Sammy has a deep sense of integrity. At nineteen, he's enthralled by the girls' clothing.... he thinks their actions are cute. In other words, through Sammy, the girls are getting exactly the reaction they'd hoped for. In any case, we also see that Sammy is compassionate and willing to put himself out there for what he believes is right. In challenging Lengel, he also gives up his job, something Lengel warns him not to do. By the end of the story, we see that Sammy comes to understand his heroics may not bode well for the future. It's great to be a hero.... but how can one be a hero if they don't have a job. Rules have a purpose, thwarting them, especially to look like a hero, leaves one unemployable.